Debt - Narrative (Details) - USD ($)		1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 21, 2020	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Aug. 20, 2020	May 26, 2020	Aug. 13, 2018	Aug. 31, 2017	Nov. 30, 2015	Oct. 31, 2013
Line of Credit Facility [Line Items]
Other short-term debt			$ 10,000,000	$ 10,000,000	$ 6,000,000
Proceeds from/(redemption of) commercial paper, net					1,094,000,000	$ 360,000,000
Repayments of Debt				1,246,000,000	2,004,000,000	0
Commercial paper			1,012,000,000	1,012,000,000	2,405,000,000
Total debt outstanding			13,918,000,000	13,918,000,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity			3,800,000,000	3,800,000,000
Additional borrowing capacity (up to)	$ 625,000,000
Debt issuance costs			4,000,000	4,000,000	9,000,000
Amount of debt outstanding			0	0
Unreserved amount			2,600,000,000	2,600,000,000
Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity			20,000,000	20,000,000
Other short-term debt			10,000,000	$ 10,000,000
Minimum
Line of Credit Facility [Line Items]
Commitment fee percentage				0.08%
Maximum
Line of Credit Facility [Line Items]
Commitment fee percentage				0.20%
Commercial Paper
Line of Credit Facility [Line Items]
Proceeds from/(redemption of) commercial paper, net					$ 1,100,000,000
Proceeds from/(repayments of) commercial paper						$ 360,000,000
Commercial Paper | Revolving Credit Facility
Line of Credit Facility [Line Items]
Funds reserved for commercial paper program			1,000,000,000	$ 1,000,000,000							$ 1,600,000,000
Funds required to support certain subsidiary clearing house commitments			$ 171,000,000	171,000,000
Repayments of Debt				1,200,000,000
Proceeds from/(repayments of) commercial paper				$ (1,400,000,000)
Weighted average interest rate				0.33%	0.40%
Commercial paper weighted average maturity period				26 days	82 days
Commercial Paper | Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Commercial paper maturities				3 days	4 days
Commercial Paper | Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Commercial paper maturities				73 days	266 days
Senior Notes
Line of Credit Facility [Line Items]
Debt issuance costs							$ 53,000,000	$ 23,000,000	$ 21,000,000	$ 8,000,000
Face amount							6,500,000,000	2,500,000,000	2,250,000,000	1,000,000,000	2,500,000,000
2023 Senior Notes (3.45% senior unsecured notes due September 21, 2023) | Senior Notes
Line of Credit Facility [Line Items]
Face amount									$ 400,000,000
Interest rate, stated percentage			3.45%	3.45%					3.45%
2028 Senior Notes | Senior Notes
Line of Credit Facility [Line Items]
Face amount									$ 600,000,000
Interest rate, stated percentage			3.75%	3.75%					3.75%
2048 Senior Notes (4.25% senior unsecured notes due September 21, 2048) | Senior Notes
Line of Credit Facility [Line Items]
Face amount									$ 1,250,000,000
Interest rate, stated percentage			4.25%	4.25%					4.25%
2018 Senior Notes (2.50% senior unsecured notes due October 15, 2018) | Senior Notes
Line of Credit Facility [Line Items]
Interest rate, stated percentage									2.50%
Aggregate principal amount to be funded upon redemption									$ 600,000,000
2022 Senior Notes | Senior Notes
Line of Credit Facility [Line Items]
Face amount										$ 500,000,000
Percentage bearing fixed interest, rate										2.35%
2027 Senior Notes | Senior Notes
Line of Credit Facility [Line Items]
Face amount										$ 500,000,000
Percentage bearing fixed interest, rate										3.10%
NYSE Notes | Senior Notes
Line of Credit Facility [Line Items]
Face amount										$ 850,000,000
Percentage bearing fixed interest, rate										2.00%
2025 Senior Notes | Senior Notes
Line of Credit Facility [Line Items]
Face amount											$ 1,250,000,000
Percentage bearing fixed interest, rate											3.75%
2023 Senior Notes (4.00% senior unsecured notes due October 15, 2023) | Senior Notes
Line of Credit Facility [Line Items]
Face amount												$ 800,000,000
Percentage bearing fixed interest, rate												4.00%
Debt Commitments to August 2025
Line of Credit Facility [Line Items]
Commitment fee percentage				0.13%
2022 Term Loan | Term Loan | Term Loan
Line of Credit Facility [Line Items]
Debt issuance costs					$ 3,000,000
Face amount	$ 750,000,000
Debt term	18 months
Interest rate, stated percentage	1.125%
2023 Senior Notes (floating rate senior unsecured notes due June 15, 2023) | Senior Notes
Line of Credit Facility [Line Items]
Face amount							1,250,000,000
2023 Senior Notes (0.70% senior unsecured notes due June 15, 2023) | Senior Notes
Line of Credit Facility [Line Items]
Face amount							$ 1,000,000,000
Interest rate, stated percentage			0.70%	0.70%			0.70%
Extinguishment of debt		$ 1,250,000,000
Interest Expense, Debt			$ 4,000,000
2032 Senior Notes (1.85% senior unsecured notes due September 15, 2032) | Senior Notes
Line of Credit Facility [Line Items]
Face amount							$ 1,500,000,000
Interest rate, stated percentage			1.85%	1.85%			1.85%
2040 Senior Notes (2.65% senior unsecured notes due September 15, 2040) | Senior Notes
Line of Credit Facility [Line Items]
Face amount							$ 1,250,000,000
Interest rate, stated percentage			2.65%	2.65%			2.65%
2060 Senior Notes (3.00% senior unsecured notes due September 15, 2060) | Senior Notes
Line of Credit Facility [Line Items]
Face amount							$ 1,500,000,000
Interest rate, stated percentage			3.00%	3.00%			3.00%
2030 Senior Notes (2.10% senior unsecured notes due June 15, 2030) | Senior Notes
Line of Credit Facility [Line Items]
Face amount								$ 1,250,000,000
Interest rate, stated percentage			2.10%	2.10%				2.10%
2050 Senior Notes (3.00% senior unsecured notes due June 15, 2050) | Senior Notes
Line of Credit Facility [Line Items]
Interest rate, stated percentage			3.00%	3.00%				3.00%
Senior Notes Due December 2020 | Senior Notes
Line of Credit Facility [Line Items]
Face amount								$ 1,250,000,000
Interest rate, stated percentage								2.75%
Extinguishment of debt				$ 14,000,000